The present invention relates to digitizer tablets having a movable cover. More particularly, the invention relates to a digitizer tablet having a hinged cover, especially a back-lighted digitizer tablet, and a support for holding the cover open.
A digitizer includes a tablet and a cursor or stylus and provides digitized signals to a computer which represent the position of the cursor or stylus on a digitizing surface of the tablet. Typically, digitizers are used with a computer to input to the computer digitized signals representing graphics, drawings, etc., or menu selection, etc. The tablet includes a grid or electrode structure adjacent the digitizing surface which interacts with the cursor or stylus as it is moved on or in close proximity to the digitizing surface. The tablet typically encloses circuitry that determines the position of the cursor or stylus relative to the digitizing surface and includes a connector for connecting the tablet to a computer.
Back-lighted digitizer tablets are particularly suitable for accurate tracing of drawings, semiconductor layouts, circuit diagrams, etc., and include structure for back-lighting the digitizing surface, somewhat in the nature of a light box. Back-lighting facilitates tracing of graphics, drawings, indicia, etc. for input to a computer from a sheet placed on the back-lighted digitizing surface using the cursor or stylus and a graphics or CAD application program loaded into the computer.
Typically, the grid or electrode structure of a back-lighted digitizer tablet is enclosed by the cover and associated structure while the lighting apparatus is disposed in a base structure, and the cover is connected to the base structure in a manner which facilitates moving the cover relative to the base structure for gaining access to the lighting apparatus for servicing it, for example for light element replacement.
A current back-lighted digitizer tablet includes a hinged cover which permits the cover to be pivoted open relative to the base structure. A single support rod used to hold the cover open is stored within the closed digitizer tablet. The support rod is pivoted at one end to the base structure and is simply swung vertically to engage and support the cover which is simply rested on the distal tip of the support rod, or vice verse. Since the rod is not attached to both the cover and the base structure and simply engages one of them due to gravity, the cover is not stably held in the open position and may easily be jarred loose and fall while a light element is being changed. If that should occur, it is possible to damage the digitizer tablet. Moreover, since the rod must manually be moved into position, there is the possibility that an operator may incorrectly position the rod which may lead to the cover falling.
Thus, there is a need for a support for holding a digitizer cover, particularly the cover to a back-lighted digitizer tablet, which stably and automatically holds the cover open.